Development of athermal and isothermalε-martensite in atomized Co-Cr-Mo-C implant alloy powders

Song, Chang‐Hwa; Park, H.; Seong, Hwan Goo; López, H. F.

doi:10.1007/bf02586154

Cited by 26 publications

(22 citation statements)

References 25 publications

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“…A maximum of 64 vol. % was reported in 80 μm water atomized Co-Cr-Mo powders ( Figure 6) [25]. The amounts of athermal ε-martensite are strongly From this work, it is evident that rapid solidification either reduces or inhibits segregation at Cr contents below 30 wt.…”

Section: Hcp and Fcc Phasesmentioning

confidence: 56%

“…A maximum of 64 vol. % was reported in 80 µm water atomized Co-Cr-Mo powders ( Figure 6) [25]. The amounts of athermal ε-martensite are strongly influenced by the annealing temperatures, with increasing volume fractions found in alloys annealed at increasing temperatures [34].…”

Section: Hcp and Fcc Phasesmentioning

confidence: 85%

“…A maximum of 64 vol. % was reported in 80 μm water atomized Co-Cr-Mo powders ( Figure 6) [25]. The amounts of athermal ε-martensite are strongly …”

Section: Hcp and Fcc Phasesmentioning

confidence: 92%

“…In this regard, the percent of ε-Co phase in investment casting alloys exhibits a value between 2 and 12 vol. % [25,27], while in hot Co-alloy forgings (10% deformation) the amount of ε-phase reached a value of 35 vol. % [10].…”

Section: Electrochemical Techniquesmentioning

confidence: 99%

“…Figure 4 shows the dimensions of the interdendritic segregation regions in as-cast Co-alloys processed by the investment casting technique [2,7,[20][21][22][23][24]. Notice that interdendritic segregation regions are on the order of 5-18 µm, but in atomized powders the interdendritic segregation diminishes down to close to 0.3 µm [25]. Figure 4 shows the dimensions of the interdendritic segregation regions in as-cast Co-alloys processed by the investment casting technique [2,7,[20][21][22][23][24].…”

Section: Electrochemical Techniquesmentioning

confidence: 99%

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Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications

Ramírez-Ledesma

López

Juárez-Islas

2016

Metals

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Binary Co-Cr alloys containing various Cr contents were vacuum induction melted and cast into wedge-shaped copper molds. It was intended to develop a microstructure (1) free from interdendritic segregation and porosity; (2) having minimal intermetallic precipitates; and (3) suitable for biomedical applications. The resultant microstructures were evaluated from sections obtained longitudinally and centrally in the plane normal to the diverging wedge faces. All ingots showed a dendritic microstructure with some characteristic features. For instance, in Co-20-30 wt. % Cr alloys, the chilled cast microstructures consisted of columnar dendrites without interdendritic segregation, a minimum of intermetallic precipitates, and the presence of a predominantly athermal HCP ε-martensite (>80 vol. %). In addition, the metastable FCC γ-Co phase was identified by X-ray diffraction and scanning electron microscopy. In the case of 35-44 wt. % Cr cobalt alloys, a eutectic constituent including the σ-phase were found to develop in the interdendritic regions. From this work, a Co-20 wt. % Cr alloy was chosen for further investigation after heat treating below the γ/ε transition temperature. The resultant tensile strength and ductility were further improved after applying a heat treatment at 730 • C for 30 min, obtaining values of elongation of 26% as compared with 2.55 < 5 of elongation in the as cast condition. Also, the alloy corrosion resistance in artificial saliva was investigated. It was found that the exhibited corrosion rates for the as-cast and heat-treated conditions are between those reported for other similar systems.

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Section: Hcp and Fcc Phasesmentioning

confidence: 56%

Section: Hcp and Fcc Phasesmentioning

confidence: 85%

“…A maximum of 64 vol. % was reported in 80 μm water atomized Co-Cr-Mo powders ( Figure 6) [25]. The amounts of athermal ε-martensite are strongly …”

Section: Hcp and Fcc Phasesmentioning

confidence: 92%

Section: Electrochemical Techniquesmentioning

confidence: 99%

Section: Electrochemical Techniquesmentioning

confidence: 99%

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Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications

Ramírez-Ledesma

López

Juárez-Islas

2016

Metals

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Thermokinetically Driven Microstructural Evolution in Laser‐Based Directed Energy‐Deposited CoCrMo Biomedical Alloy

et al. 2022

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The present work investigated additive manufacturing of CoCrMo alloy via laser‐based directed energy deposition process. A range of five different laser powers are used for the fabrication of fully dense and metallurgically sound CoCrMo samples. The solidification parameters including temperature gradient, growth rate, and the cooling rate are computationally predicted in each case, using a multitrack multilayer model. The variation in these computationally predicted solidification parameters with the different laser powers used in fabrication is linked to the evolution of microstructural features within the laser additively deposited CoCrMo samples. Evolution of ε‐hexagonally close‐packed (HCP) martensites from γ‐face‐centered cubic (FCC) phase, along with variation in thickness of these martensitic laths with respect to the varying solidification parameters associated with the laser additive deposition, is identified and investigated. The multitrack, multilayer thermokinetic model not only provides the spatial and temporal signatures of laser‐based directed energy deposited process, but uniquely considers the influence of pre‐ and postheating on microstructural evolution with their correlation with experimental observations.

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Martensitic Transformation in a Cast Co-Cr-Mo-C Alloy

López

Saldívar-García²

2007

Metall Mater Trans A

113

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The face-centered-cubic (fcc) to hexagonal close-packed (hcp) martensitic transformation exhibited by an as-cast Co-Cr-Mo-C alloy was investigated in this work. The alloy was annealed at 1150°C, water quenched, and then isothermally aged at 700°C to 900°C. Quantitative measurements of transformed hcp martensite (also known as e-martensite) as a function of time and temperature were used in plotting C curves describing the transformation kinetics. Moreover, microstructural characterization indicated that the transformation exhibited two distinctive e-martensite morphologies. In the neighborhood of coarse carbides, multiple nucleation events were linked to the formation of e-martensite, while in the bulk of the dendrite matrix, the dominant morphology was as straight plates. Kinetic determinations of activation energies, Q, in either region indicated that in platelike e-martensite, Q = 57.24 kcal/mol, but in ''pearlite''-like morphologies, Q = 37.88 kcal/mol. Apparently, as the activation energy was reduced, multiple nucleation events were favored leading to the ''pearlitic'' appearance.

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Development of athermal and isothermalε-martensite in atomized Co-Cr-Mo-C implant alloy powders

Cited by 26 publications

References 25 publications

Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications

Evaluation of Chill Cast Co-Cr Alloys for Biomedical Applications

Thermokinetically Driven Microstructural Evolution in Laser‐Based Directed Energy‐Deposited CoCrMo Biomedical Alloy

Martensitic Transformation in a Cast Co-Cr-Mo-C Alloy

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